The present invention relates generally to prosthetic devices and, more particularly, to an alignment device for providing angular adjustment of a prosthetic limb in forward and rearward directions to obtain a customized fit for the wearer.
Various devices have been developed to provide alignment for prosthetic limbs, such as a prosthetic lower leg worn by a below-the-knee amputee. The limb is typically adjustably attached to a prosthetic knee socket for providing a rigid leg support. The alignment devices are designed to permit angular adjustment of the limb in a forward-rearward plane below the prosthetic knee socket to approximate the proper toe-to-heel pitch and gait for the wearer. Proper fit of the prosthetic limb is necessary for the full range of motion and activity of the wearer to avoid undesirable health risks, particularly in diabetic amputees that are susceptible to irritation in areas on and around the residual limb common to amputees. This irritation primarily results from improper loading on the rigid prosthetic knee socket that causes excessive pressure in areas of the residual limb.
In the past, alignment devices have been designed that mount between a lower end of a prosthetic socket and an upper end of a prosthetic limb. The prosthetic limb may include a leg portion and a leaf-spring foot portion. In general, the leg and foot portions of the prosthetic limb are rigid members, although some elastic energy absorbing members may be provided to help absorb shock as the wearer goes through conventional motions.
In one known alignment approach for prosthetic limbs, such as those of the laminated plate-type as disclosed in U.S. Pat. Nos. 4,547,913 and 4,822,363, the limb is attached to a mounting flange extending downwardly from the prosthetic knee socket. A prosthetist angularly aligns the limb in forward and rearward directions by inserting various angled wedge or shim adaptors between an upper end of the limb and a lower end of the mounting flange. Shim adaptors of varying angles are tested by the prosthetist until one providing the most favorable toe-to-heel pitch and gait for the wearer is identified.
In another known alignment approach, the prosthetic limb is connected to the prosthetic socket through a rotational joint, such as a rotatable socket adaptor or pair of sliding curved plates. During the custom fitting process, the prosthetist rotationally adjusts and aligns the prosthetic limb relative to the knee socket to the desired angular position for proper toe-to-heel pitch and gait. Typically, the alignment procedure requires multiple adjustments to the alignment device with adjustment tools.
In each of the alignment approaches described above, the wearer may be restricted to the toe-to-heel pitch set by the prosthetist after the custom fitting process, and the wearer may have limited ability to readily adjust the angular setting of the limb as may be desired, particularly when changing between shoes of different heel height. When the wearer does attempt to make an alignment adjustment, that adjustment may affect other adjustments already set on the prosthetic limb, thereby adding to the complexity of the adjustment process. To avoid making complex manual adjustments to the alignment device for accommodating shoes of different height, the wearer may insert padding, shims or other adjustment devices into the shoes which improves the fit but may not achieve the optimum toe-to-heel pitch and gait for the particular shoe. Alternatively, the wearer may simply decide to wear shoes of only one heel height.
Thus, there is a need for a prosthetic limb alignment device that is readily manually adjustable by the wearer to optimize the toe-to-heel pitch and gait of the wearer.
There is also a need for a prosthetic limb alignment device that is readily manually adjustable by the wearer to accommodate for shoes of different heel heights while providing the optimum toe-to-heel pitch and gait for the wearer.
There is yet another need for a prosthetic limb alignment device that may be readily manually adjusted by the wearer without requiring adjustment tools.
There is yet also a need for a prosthetic limb adjustment device that is readily manually adjustable without affecting other adjustments set on the prosthetic limb.
The present invention overcomes the foregoing and other shortcomings and drawbacks of alignment devices and methods heretofore known. While the invention will be described in connection with certain embodiments, it will be understood that the invention is not limited to these embodiments. On the contrary, the invention includes all alternatives, modifications and equivalents as may be included within the spirit and scope of the present invention.
In accordance with the principles of the present invention, an alignment device and method are provided for aligning a prosthetic limb worn by an amputee. The alignment device may be used in a below-the-knee amputation environment wherein it is mounted between a lower end of a prosthetic socket and an upper end of a prosthetic limb. The alignment device is particularly designed to provide angular alignment of the prosthetic limb in forward and rearward directions below the knee socket to optimize the toe-to-heel pitch and gait for the wearer as shoes of different height are worn. Other adjustments of the prosthetic limb relative to the prosthetic knee socket are also possible with the alignment device of the present invention.
The alignment device includes a mounting mechanism that is adapted to be affixed to a prosthetic knee socket, mechanical knee or other prosthetic device. A prosthetic limb is operatively connected to the mounting mechanism and is adapted to move in forward and rearward directions in an anterior-posterior plane upon adjustment of the alignment device. An extendable and retractable positioning mechanism is operatively connected to the mounting mechanism and the prosthetic limb. The prosthetic limb is angularly aligned in the anterior-posterior plane upon extension and retraction of the positioning mechanism. The positioning mechanism may include a manually adjustable turnbuckle assembly, hydraulic actuator, electric actuator or other adjustment device that is readily accessible on the alignment device to permit adjustments by the wearer.
The alignment device of the present invention is intended to give the wearer more control and adaptability over the types of shoes that may be worn. The alignment device of the present invention provides the ability to change the loading on the knee socket in such a way that it provides less irritation to areas on or around the residual limb common to amputees. Moreover, the alignment device of the present invention gives the wearer a readily adjustable heel-to-toe configuration without disturbing any other fixed adjustments on the prosthetic limb, and without requiring adjustment tools.
The above and other objects and advantages of the present invention shall be made apparent from the accompanying drawings and the description thereof.